1. Field of the Invention
This invention relates to the determination of the position of a body and more particularly, but not exclusively, is concerned with the determination of the position within a guidance beam of a moving body, e.g. missile, in order that the body may pursue a predetermined path along the beam.
2. Prior Art
British Patent Specification No. 1395246 describes a method of, and apparatus for, sensing the position of a body, the apparatus described specifically and illustrated in the specification having a reticle which shutters the beam progressively. This shuttering restricts the radiance of the transmitted beam and it is an object of the invention to ameliorate this disadvantage of the prior art system.